Interactions between Fungus‐Growing Ants (Attini), Fruits and Seeds in Cerrado Vegetation in Southeast Brazil¹

Abstract

We surveyed the material collected for fungus culturing by attine ants in the cerrado vegetation of southeast Brazil. Six genera of the so‐called lower attines (Cyphomyrmex, Mycetarotes, Mycocepurus, Myrmicocrypta, Sericomyrmex and Trachymyrmex) collect a wide variety of plant material as fungal substrate. Plant diaspores of nonmyrmecochorous species comprise a large portion of the items brought to the nest, especially in the rainy season. Removal experiments using fruits of selected plant species revealed that attine ants (including the leaf‐cutters Atta and Acromyrmex) not only actively clean the seeds (remove fruit pulp), but also carry them up to 12 m in the cerrado. Germination tests showed that removal of fruit pulp by attine ants increases germination rate in Ocotea pulchella (Lauraceae), Prunus sellowii (Rosaceae), Ouratea spectabilis (Ochnaceae), Rapanea umbellata (Myrsinaceae) and Psychotria stachyoides (Rubiaceae). For P. stachyoides, however, ants had no effect on germination if seeds had already passed the digestive tract of birds. Aril removal by attines also increases germination success of Copaifera langsdorffii (Leguminosae) and Virola sebifera (Myristicaceae) seeds. The results indicate that attine‐fruit/seed interactions are particularly conspicuous in the cerrado, suggesting that fungus‐growing ants may play a relevant role in fruit/seed biology in this vegetation type. Potential ant‐derived benefits to diaspores of nonmyrmecochorous plants in the cerrado would include secondary seed dispersion and/or increased germination success by ant‐handled seeds.

Insect-plant interactions: new pathways to a better comprehension of ecological communities in Neotropical savannas

“…But it does not end at this point, as to the present examples or to other similar ones (e.g. leaf-cut ants and plants - Leal & Oliveira 1998; herbivores (galls) and infl orescences -Fernandes et al 2005; Termites, dung beetles and plants - Rosa et al 2008, Freymann et al 2008. Community ecology needs additional answers to two main questions: how conservative are multitrophic interactions in terms of space and time?…”

“…However, considering insect-plant interactions and its implications in food webs and multitrophic relationships, the number of papers is still now almost insignifi cantly when compared to temperate areas (e.g. Oliveira 1997, Leal & Oliveira 1998, Del-Claro & Oliveira 2000, Fernandes et al 2005, Freymann et al 2008, Rosa et al 2008. Indeed, only one study (Oliveira & Del-Claro 2005) deeply examined the whole natural history and ecology of a plant-arthropod interaction (ants-membracid-plant-herbivores) with its implications to all related members.…”

Anthropogenic effects on interaction outcomes: examples from insect-microbial symbioses in forest and savanna ecosystems

“…In addition, leaf-cutting ant colonies, through deposition of seeds in their dumps, can play a significant role in seedling recruitment during the dry season (Farji-Brener and Ghermandi 2004). Although less is known about the ecological role and impact of the lower attines, at least one study has documented a beneficial effect of these ants in dispersal of seeds from non-myrmecophyte plants (Leal and Oliveira 1998).…”

Patterns of diversity and abundance of fungus-growing ants (Formicidae: Attini) in areas of the Brazilian Cerrado

“…For instance, in the Brazilian Atlantic Rain Forest, seed cleaning by Mycocepurus goeldii Forel, 1893 was found to increase the germination rate of Hymenaea courbaril Linnaeus, 1758 seeds (OLIVEIRA et al 1995). Similarly, in the Cerrado, attine ants act as secondary dispersers of seeds of non-myrmecochorous plants (CHRISTIANINI et al 2007) and also increase their germination success (LEAL & OLIVEIRA 1998).…”